1. Field of Invention
This invention relates to an apparatus for measuring the gas leakage of a container and more particularly to apparatuses for measuring gas leakage of a container utilizing balance beams.
2. Prior Art
It is frequently necessary to measure the gas tightness of containers which are used to store gases under pressure. Among the various devices that exists in the prior art for measuring gas leakage, the ones that utilize a balance mechanism and the pressure difference between the inside and outside of a floating cup coupled to the balance mechanism are most suitable for precision measurement. Gas leakage in such devices is measured by connecting the container to be measured to the apparatus, introducing a reference pressure inside the floating cup, introducing a pressure outside the cup and in the container to be checked, balancing the balance mechanism and measuring the amount that the floating cut rises caused by the increased force acting on the floating cup in response any decrease in the gas pressure outside the cup as a result of a leakage in the test container. However, since leakage measurement of gases in a container is a continuous operation, it is conducted in the prior art cyclically in the following manner: After the first measurement, the gas at the preference pressure inside the cup is released to reset the balance beam to the equilibrium, horizontal position and the previous described measurement steps are repeated again. From these cyclic measurements the amount of leakage is approximated from the period of repetition of the measurements.
Since the amount of gas leakage is approximated from the period of repetition, it is difficult to achieve a measurement of gas leakage which has a high precision. Furthermore, in such devices, the pressure difference between the inner and outer surfaces of the floating cup due to the unbalance of the balance beam constitutes a source of error in the quantitive measurements.